Hello Julio.
What control this in TRM is called Position Manager. It has two main components Original and derived.
In your example, When you carry out a decrease The sap calculate the realized foreign exchange gain/loss (as a derived component). The lines of 900.000 and 639.771,62 in your screenshot. These business transactions remain in the Planned status (column Status at T. Code tpm13)
For posting purposes, you must use the Fix and Post Derived Business T.Code TPM18.
If you have doubt about account determination here, let me know.
This makes sense once the decrease and increase should not be considered for valuation propose (TPM1).
In response "It is any chance we can take them out into account in the valuation process in tpm1" Yes you can. But doesn't make sense.
The IMG active for this is "Assignment of Update Types to Position Change Categories"
Best